1. Field of the Invention
The present invention relates to a zoom lens system in particular to a zoom lens system with a high zoom ratio.
2. Related Background Art
As a zoom lens system with a high zoom ratio, it has been known a five-group type zoom lens composed of, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power, for example, by Japanese Patent Application Laid-Open Nos. 8-179213 and 9-304697.
However, when a zoom lens having a short focal length is to be constructed on the basis of a zoom lens disclosed by Japanese Patent Application Laid-Open No. 8-179213, it is difficult to secure sufficient amount of back focal length.
Moreover, since a first lens group, a second lens group, a third lens group, and a fourth lens group of a zoom lens disclosed by Japanese Patent Application Laid-Open No. 9-304697 have strong refractive power, it becomes difficult to correct aberrations.